There is increased demand for greater equipment densities in data centers, which in turn leads to increased heat load in the data center. The equipment racks or enclosures in data centers are often located in parallel rows, where aisles are defined by two rows of racks. The equipment racks can be different widths, heights and depths. For efficient operation, it is necessary to supply cold air to the racks (in some cases without mixing the cold air with the room air), and direct heated air leaving the racks from the room without mixing the heated air with the cold air or the room air.
Custom-designed solutions for aisle enclosure are often required to couple the variably sized and shaped equipment racks to the data center's ceilings and ductwork. These solutions may not only be expensive to implement, but may also be difficult to reconfigure when the data center is rearranged or when equipment racks or enclosures are added or removed.